CA1114214A - Procedure and means for preparing thermogroundwood - Google Patents
Procedure and means for preparing thermogroundwoodInfo
- Publication number
- CA1114214A CA1114214A CA343,494A CA343494A CA1114214A CA 1114214 A CA1114214 A CA 1114214A CA 343494 A CA343494 A CA 343494A CA 1114214 A CA1114214 A CA 1114214A
- Authority
- CA
- Canada
- Prior art keywords
- steam
- chips
- grinder
- lock feeder
- thermogroundwood
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 238000000034 method Methods 0.000 title claims abstract description 22
- 238000010025 steaming Methods 0.000 claims abstract description 15
- 238000000227 grinding Methods 0.000 claims abstract description 12
- 239000002023 wood Substances 0.000 claims abstract description 9
- 238000007599 discharging Methods 0.000 claims abstract description 6
- 238000003860 storage Methods 0.000 claims abstract description 5
- 238000010438 heat treatment Methods 0.000 claims abstract 5
- 238000004519 manufacturing process Methods 0.000 claims description 4
- JTJMJGYZQZDUJJ-UHFFFAOYSA-N phencyclidine Chemical class C1CCCCN1C1(C=2C=CC=CC=2)CCCCC1 JTJMJGYZQZDUJJ-UHFFFAOYSA-N 0.000 claims description 2
- 239000000835 fiber Substances 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- 238000005260 corrosion Methods 0.000 description 3
- 230000007797 corrosion Effects 0.000 description 3
- 238000009434 installation Methods 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 229920001131 Pulp (paper) Polymers 0.000 description 2
- 230000002349 favourable effect Effects 0.000 description 2
- 229920005610 lignin Polymers 0.000 description 2
- 241000196324 Embryophyta Species 0.000 description 1
- 241000218657 Picea Species 0.000 description 1
- 235000011054 acetic acid Nutrition 0.000 description 1
- 150000001243 acetic acids Chemical class 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 150000007513 acids Chemical class 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 206010061592 cardiac fibrillation Diseases 0.000 description 1
- 229920002678 cellulose Polymers 0.000 description 1
- 239000001913 cellulose Substances 0.000 description 1
- 230000002860 competitive effect Effects 0.000 description 1
- 238000009833 condensation Methods 0.000 description 1
- 230000005494 condensation Effects 0.000 description 1
- 230000003111 delayed effect Effects 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000002600 fibrillogenic effect Effects 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 241000894007 species Species 0.000 description 1
- 239000004575 stone Substances 0.000 description 1
- LENZDBCJOHFCAS-UHFFFAOYSA-N tris Chemical compound OCC(N)(CO)CO LENZDBCJOHFCAS-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21B—FIBROUS RAW MATERIALS OR THEIR MECHANICAL TREATMENT
- D21B1/00—Fibrous raw materials or their mechanical treatment
- D21B1/04—Fibrous raw materials or their mechanical treatment by dividing raw materials into small particles, e.g. fibres
- D21B1/12—Fibrous raw materials or their mechanical treatment by dividing raw materials into small particles, e.g. fibres by wet methods, by the use of steam
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/10—Greenhouse gas [GHG] capture, material saving, heat recovery or other energy efficient measures, e.g. motor control, characterised by manufacturing processes, e.g. for rolling metal or metal working
Landscapes
- Engineering & Computer Science (AREA)
- Life Sciences & Earth Sciences (AREA)
- Wood Science & Technology (AREA)
- Mechanical Engineering (AREA)
- Paper (AREA)
- Disintegrating Or Milling (AREA)
Abstract
Abstract of the disclosure Procedure for preparing thermogroundwood from wood chips, wherein the chip flow is conducted from a storage magazine under normal pressure through a lock feeder into a pressurized steaming chamber, where the chips stay for a few minutes and are heated to optimum temperature 100 to 125 Centigrade, and from the steaming chamber through a lock feeder to a feed means which supplies the chips into a hot grinder of enclosed design. In the procedure the steam dis-charging from the throat of the grinder against the chip flow is utilised towards heating the chips in the steaming chamber, and the steam separated from the groundwood is to the purpose of its utilization conducted. The steam utilized for heating the chips is conducted in complete counter-current fashion with regard to the chip flow, that is through the feed means, lock feeder, steaming chamber, lock feeder and magazine under normal pressure into free atmosphere, and that the grinding of the chips is carried out at a substantially higher temperature than the heating of the chips.
Description
:"
The proportion of mechanical pulps as ra~ material in the manufai~t4~ing ofpaper has been rapiclly increasing over recent years. The competitive qu3lity of mechanical pulps was mainly created by the pulp brand called thermogroundwood, which is produced by attrition-grinding wood splinters betwoen two grinder disks. In the preparation of thermogroundwood an olevated temperature is used in order that the lignin might soften and the fibres might separate without being ruptured. In addition, fibre friction work takes place between the grinder disks, and this favourably fibrillates the fibres, together with the fibre/grinder disk friction ~ork. This fibrillation of fibres endows the paper made of such pulp stock with greater strength than does the fibre produced in cold attrition grinding or in stone grinding. This manufacturing method has been known ;n principle long already. Only in the most recent years has the procedure begun to be more widely adopted~ The cause of such development have been, in the first place, the increase in price of the wood ra~ material and the technical developmont of the thermogroundwood producing equ;p~ent.
While the thermogroundwood technoLogy has been rapidly developing, attention has also begun to be paid to the high consumption of electricity in this process. A typical thermogroundwood installation consumes about 180~ to 2003 k~lh of electric energy per ton of pulp. Since evidently the efficiency of the defibration itself is w3y below lX, virtu3lly all of the axle power that is put in is converted to heat. But, as it is generally judged, heat is no useful ~'~
z~
utility in itself: its usability depends on how far its ternporature exceeds that of the next sourc of heat with abuniant avaiLability.
It is ger)erally stated regardin3 thermogroundwood processes that as soon as the temperatura rises over a certain limit, for instance 127 Centigrade for spruce, the lignin will soften excessively and spread as 3 molten product over the surface of ~he fibre material that is being ground, thereby prevent;ng the formation in the paper manufacturing process of the hydrogen bridges, which are typical of cellulose. Owing to this, in favourably operat;ng thermogroundwood installations the temperature 3nd the equivalent saturated water vapour pressure are controlled to be such that this temperature ;s not surp3ssed. A typically favourable preheatin3 and grinding pressure actu3lly used is about 120 Centigrade and the equivalent steam ?ressure, about 2ûO
kPa.
However, these temperatures and pressures mentioned do not yet enable the usability of said steam in typical steam consumption objects. It is, naturally, always possible to compress steam of arbi-trary pressure to 3ny given pressure and tem?erature, but this involves separate extra costs. One has recovered heat from steams with pressure as mentioned, by contacting the steam with water~ whereby hot w3ter is obtained. 3ut as a rule hot water of 70 to O Centigrade is a commodity found in abundance in paper mills.
The heat recovery systems of m3ny thermoground~lood processes have ~oreover been encumbered by the part;cular drawback that the steam obtained either directly from the grinder or from the grinder through a preheater contains large amounts of air, in fact typically 10% by volume. If it is contemplated, e.g. out of corrosion considerations, to exchange this steam for pure steam, major difficulties will be experienced in the exchange process ow;ng to the low condensation heat transfer coefficient implied by the air content.
The object of the present ;nvention is therefore a procedure for the prep3ring of thermogroundwood from wood chips and wherein the chip flow is conducted from storage under normal pressure through a lock feeder into a pressurized s~eaming chamber, where the chips are delayed a few minutes and heated to optimum temperature 10û to 125 Centigrade, and from the steam;ng chamber through a lock feeder into a feeding means suoplying the chips into a hot grinder of enclosed design, and in said procedure the steam discharging from the throat of the grinder against the ch;p flo~l being employed to heat the chips in the steam;n~ charlber, and the steam separated from th2 grounluood being conducted, to the purpose o-f its utilisation, to 3 heat exch3nger.
The object of the invention is: to provide an ideal therrnogroundwoo-Jm3nufacturing process wherein the highest possible fraction of the axle input power can ~e recovered in the form of steam as pure as possible an~J which may be removed from the installation at the highest poss;ble temperature.
The procedure of the invention is ch3racteriz2d in that the steam used to heat the chips is conducted in complete counter-current fashion with reference to the chip flo~, that is through a feed means, a lock feeder, a steaming chamber, a lock feed2r and a storage magazine under normal pressure into atmosphere, and that the grinding of chips is carried out at a temperature substantially higher than that at which the chips are be;ng heated.
The exper;ments which led to the present invention revealed that steam conducted in complete counter-current to the chip flo~ effectively prevents the entraining of air in the process. lt is important with a view hereto that this part of the steam ;s 3lso conducted throùgh the chip magaz;ne under normal pressure. The steam will then contain air in abundance, for ~hich reason it is freely voided.
It has been found unexpectedly that in the grinder itself the temperature in itself is no decisive factor regarding the covering of the fibres with softened l;gnin. Therefore, as taught by the present invention, the grinding is performed at a temperature substantially higher than that of the chip preheating. As a consequence, the steam to be recovered will be obtained at a substantially higher temperature than heretofore. Moreover, the recovered steam contains air only bet~een 0.1 and 0-06~ by volume. Thus, the air content is a min;mal fract;on of that in procedures of prior art. This lo~l air qu~ntity enables the steam of relatively high pressure to be utilised at typical steam us;ng points of the plant.
.
A favourable embodiment of the invention is characterized in that part of the steam discharging to the feed means from the throat of the gr;nder is conducted to a heat exchanger and that to the purpose of controll;ng the grinding temperature this steam flo~ is more or less strongly throttled. The .
r greater the throttling appl;ed to the steam flow, the h;gher will the grind;ng temper3ture rise. The grindirlg is most appropriately carried out at a temporature at least 135 Centigrade. This lower temperature lim;t carries signi~icance in the respect that the nearly airless steam ob-tained contains, for ;nstance, forlnic and acetic acids, w'nich give rise to corrosion, and resinand fatty ac;ds, which are deposited on the heat exchange surfaces and produce d;rt layers on tham which hamper the heat transfer. It has unexpactedly been found ;n exporiments that were carried out, that corrosion and typical soiling of the hea-t transfer surfaces no longer occur in practice ;f the temperature of the condensin3 unclean steam is not less than 135 Cent;grade. This ;s believed to be explainable by the c;rcumstance that water confJensing at a higher temperature is better able to dissolve the sa;d acids and will therefore, as ;t escapes from the heat transfer surface, continuously carry off such dirt deposits.
The present invention also concerns a means for carryin3 out the procedure, comprising for the chip flow a m3gazine under normal pr-ssure, a lock feeder, a steaming cha~ber, a lock feeder, 3 feed means, and one or several consecutive hot grinde'rs, after each such grinder being disposed a cyclone for separating the steam from the groundwood, the steam being conducted from such cyclones to a joint heat exchan3er. The means is characterized in that the feed means of the first grinder is connected by a steam conduit fitted with throttl;ng valve, to a heat exchan3er.
The invention is described in the following with the aid of an example~ with reference being made to the a~tached drawing presenting, schematically, an embodiment of the procedure.
In the drawing, reference numeral 1 indicates the chip magazine under atmospheric pressure, and into ~hich are supplied chips in the direction indicated by the arrow 2. The numeral 3 refers to a lock feeder, which feeds a constant rate chip flow into the steaming chamber 4. On the other hand, the Lock feeder 3 feeds, in the opposite direction, a steam flow, which preheats the chips residincl in the magazine 1 and pushes out air therefrom. In the steaming chamber 4, the chips are heated to optimum defibrating temperature, which is freely selectable in 3ccordance with the operating principle of the system. For instance when manu-facturing newsprint pulp, this temperature will be 100 to 125 Centigrade, deponding on timber species. The chips stay a few , .' ' ` ' ' '. ''. `''. ' `' ' .. '`:
~$~
PA~E 5 minutes in the steanlin~ ch3mber, yet so that the timn of stay of all particles is 3pproximately the same. The ch;ps dep3rt from the steaming ch3mber 4 as a constant rate flo~ through the lock feeder S into the feed means 6, which has not been more closely depicted, but which may be a screw conveyor, known in itself in this connection. At the same time, the lock feeder 5 feeds steam from the feed means 6 into the steaminy ch3mber 4.
The feed means 6 continuously pushes chips into the throat of the hot gr;nder 7 of enclosed design. The grinder 7 generates steam, of which part dep3rts along with the groundwood through the grinder's periphery. Another part of the steam escapes through the throat of the grinder, against the chip flow. Part of this steam, again, passes through the feed me3ns 6, the lock feeder 5, the steaming chamber 4, the lock feeder 3 and the chip m3gazine 1 into free atmosphere. Since th;s part o-f the steam runs completely counter-current to the chip flow, it serves efficiently to remove air from the system. Another part of the steam dischargin3 from the throat of the grinder 7 is conducted through the steam conduit 9, fitted ~ith throttling va~ve 8, into a heat exchanger 10, preferably of the condenser/evaporator type. The throttling valve 8 is used to controL the tempera-ture~n~fpressure in the grinder 7. The valve 8 is throttled to such extent that grinding will take place at a temperature not lower than 135 Centigrade, whereby the equivalent pressure in the gr;nder will be at least 350 kPa. In the trials performed up to now, no upper limit for the temperature or pressure has been found. It is obvious, at all events, that th~ usability of the steam g3ined from the process increases with increasing temperature and pressure. On the other hand, the temperature cannot be raised to any great height without damaging the fibres.
The groundwood derived from the grinder 7, which is accompanied by steam, departs from the grinder's periphery through the conduit 11 to the cyclone 12.
Here, the groundwood settles do~nwardly, and the steam goes through the steam conduit 14, provided with throttling valve 13, to the heat exchanger 10. The feed means 15 and grinder 16 may be of the same kind as the feed means 6 and grinder 7 presented before. The steam discharging from the throat of the grinder 16 against the groundwood flow goes through the feed means 15, cyclone 12 and steam conduit 14 to the heat exchanger 10.
The finished groundwood, accompanied by steam, departs from the periphery of the grinder 16 through the conduit 17 to the cyclone 18, hhere the steam .
,. . . . .
~ . ~ : . . .
~ PAGE 6 separates and goes through the conduit 20~ provided with throttling valve 19, to the heat exchanger 10. The groundwood settles do~"nwardly in the cyclone 1 and departs through the lock feeder 21 int~ tne conttl;ner 22, whence it may be transportad to any desired point~ It is clear that hereby a slight over-pressure prevails in the container 22, and ~hich discharges as the arro 23 shows. Hereby the entrance o-f air into the process is prevented. The dry matter content of the pulp in the container 22 is about 45~, or higher~
It is obvious to a person skilled ;n the art that different embodiments of the invention may vary within the scope of the claims following below. It has been disclosed in the foregoing, and d2monstrated in the drawing, that -the process co,nprises two consecutive grinders 7 and 16, but the invention may also be applied in connection with a process comprising in consecu-t;ve arrangement more than two grinders.
"~ : ,
The proportion of mechanical pulps as ra~ material in the manufai~t4~ing ofpaper has been rapiclly increasing over recent years. The competitive qu3lity of mechanical pulps was mainly created by the pulp brand called thermogroundwood, which is produced by attrition-grinding wood splinters betwoen two grinder disks. In the preparation of thermogroundwood an olevated temperature is used in order that the lignin might soften and the fibres might separate without being ruptured. In addition, fibre friction work takes place between the grinder disks, and this favourably fibrillates the fibres, together with the fibre/grinder disk friction ~ork. This fibrillation of fibres endows the paper made of such pulp stock with greater strength than does the fibre produced in cold attrition grinding or in stone grinding. This manufacturing method has been known ;n principle long already. Only in the most recent years has the procedure begun to be more widely adopted~ The cause of such development have been, in the first place, the increase in price of the wood ra~ material and the technical developmont of the thermogroundwood producing equ;p~ent.
While the thermogroundwood technoLogy has been rapidly developing, attention has also begun to be paid to the high consumption of electricity in this process. A typical thermogroundwood installation consumes about 180~ to 2003 k~lh of electric energy per ton of pulp. Since evidently the efficiency of the defibration itself is w3y below lX, virtu3lly all of the axle power that is put in is converted to heat. But, as it is generally judged, heat is no useful ~'~
z~
utility in itself: its usability depends on how far its ternporature exceeds that of the next sourc of heat with abuniant avaiLability.
It is ger)erally stated regardin3 thermogroundwood processes that as soon as the temperatura rises over a certain limit, for instance 127 Centigrade for spruce, the lignin will soften excessively and spread as 3 molten product over the surface of ~he fibre material that is being ground, thereby prevent;ng the formation in the paper manufacturing process of the hydrogen bridges, which are typical of cellulose. Owing to this, in favourably operat;ng thermogroundwood installations the temperature 3nd the equivalent saturated water vapour pressure are controlled to be such that this temperature ;s not surp3ssed. A typically favourable preheatin3 and grinding pressure actu3lly used is about 120 Centigrade and the equivalent steam ?ressure, about 2ûO
kPa.
However, these temperatures and pressures mentioned do not yet enable the usability of said steam in typical steam consumption objects. It is, naturally, always possible to compress steam of arbi-trary pressure to 3ny given pressure and tem?erature, but this involves separate extra costs. One has recovered heat from steams with pressure as mentioned, by contacting the steam with water~ whereby hot w3ter is obtained. 3ut as a rule hot water of 70 to O Centigrade is a commodity found in abundance in paper mills.
The heat recovery systems of m3ny thermoground~lood processes have ~oreover been encumbered by the part;cular drawback that the steam obtained either directly from the grinder or from the grinder through a preheater contains large amounts of air, in fact typically 10% by volume. If it is contemplated, e.g. out of corrosion considerations, to exchange this steam for pure steam, major difficulties will be experienced in the exchange process ow;ng to the low condensation heat transfer coefficient implied by the air content.
The object of the present ;nvention is therefore a procedure for the prep3ring of thermogroundwood from wood chips and wherein the chip flow is conducted from storage under normal pressure through a lock feeder into a pressurized s~eaming chamber, where the chips are delayed a few minutes and heated to optimum temperature 10û to 125 Centigrade, and from the steam;ng chamber through a lock feeder into a feeding means suoplying the chips into a hot grinder of enclosed design, and in said procedure the steam discharging from the throat of the grinder against the ch;p flo~l being employed to heat the chips in the steam;n~ charlber, and the steam separated from th2 grounluood being conducted, to the purpose o-f its utilisation, to 3 heat exch3nger.
The object of the invention is: to provide an ideal therrnogroundwoo-Jm3nufacturing process wherein the highest possible fraction of the axle input power can ~e recovered in the form of steam as pure as possible an~J which may be removed from the installation at the highest poss;ble temperature.
The procedure of the invention is ch3racteriz2d in that the steam used to heat the chips is conducted in complete counter-current fashion with reference to the chip flo~, that is through a feed means, a lock feeder, a steaming chamber, a lock feed2r and a storage magazine under normal pressure into atmosphere, and that the grinding of chips is carried out at a temperature substantially higher than that at which the chips are be;ng heated.
The exper;ments which led to the present invention revealed that steam conducted in complete counter-current to the chip flo~ effectively prevents the entraining of air in the process. lt is important with a view hereto that this part of the steam ;s 3lso conducted throùgh the chip magaz;ne under normal pressure. The steam will then contain air in abundance, for ~hich reason it is freely voided.
It has been found unexpectedly that in the grinder itself the temperature in itself is no decisive factor regarding the covering of the fibres with softened l;gnin. Therefore, as taught by the present invention, the grinding is performed at a temperature substantially higher than that of the chip preheating. As a consequence, the steam to be recovered will be obtained at a substantially higher temperature than heretofore. Moreover, the recovered steam contains air only bet~een 0.1 and 0-06~ by volume. Thus, the air content is a min;mal fract;on of that in procedures of prior art. This lo~l air qu~ntity enables the steam of relatively high pressure to be utilised at typical steam us;ng points of the plant.
.
A favourable embodiment of the invention is characterized in that part of the steam discharging to the feed means from the throat of the gr;nder is conducted to a heat exchanger and that to the purpose of controll;ng the grinding temperature this steam flo~ is more or less strongly throttled. The .
r greater the throttling appl;ed to the steam flow, the h;gher will the grind;ng temper3ture rise. The grindirlg is most appropriately carried out at a temporature at least 135 Centigrade. This lower temperature lim;t carries signi~icance in the respect that the nearly airless steam ob-tained contains, for ;nstance, forlnic and acetic acids, w'nich give rise to corrosion, and resinand fatty ac;ds, which are deposited on the heat exchange surfaces and produce d;rt layers on tham which hamper the heat transfer. It has unexpactedly been found ;n exporiments that were carried out, that corrosion and typical soiling of the hea-t transfer surfaces no longer occur in practice ;f the temperature of the condensin3 unclean steam is not less than 135 Cent;grade. This ;s believed to be explainable by the c;rcumstance that water confJensing at a higher temperature is better able to dissolve the sa;d acids and will therefore, as ;t escapes from the heat transfer surface, continuously carry off such dirt deposits.
The present invention also concerns a means for carryin3 out the procedure, comprising for the chip flow a m3gazine under normal pr-ssure, a lock feeder, a steaming cha~ber, a lock feeder, 3 feed means, and one or several consecutive hot grinde'rs, after each such grinder being disposed a cyclone for separating the steam from the groundwood, the steam being conducted from such cyclones to a joint heat exchan3er. The means is characterized in that the feed means of the first grinder is connected by a steam conduit fitted with throttl;ng valve, to a heat exchan3er.
The invention is described in the following with the aid of an example~ with reference being made to the a~tached drawing presenting, schematically, an embodiment of the procedure.
In the drawing, reference numeral 1 indicates the chip magazine under atmospheric pressure, and into ~hich are supplied chips in the direction indicated by the arrow 2. The numeral 3 refers to a lock feeder, which feeds a constant rate chip flow into the steaming chamber 4. On the other hand, the Lock feeder 3 feeds, in the opposite direction, a steam flow, which preheats the chips residincl in the magazine 1 and pushes out air therefrom. In the steaming chamber 4, the chips are heated to optimum defibrating temperature, which is freely selectable in 3ccordance with the operating principle of the system. For instance when manu-facturing newsprint pulp, this temperature will be 100 to 125 Centigrade, deponding on timber species. The chips stay a few , .' ' ` ' ' '. ''. `''. ' `' ' .. '`:
~$~
PA~E 5 minutes in the steanlin~ ch3mber, yet so that the timn of stay of all particles is 3pproximately the same. The ch;ps dep3rt from the steaming ch3mber 4 as a constant rate flo~ through the lock feeder S into the feed means 6, which has not been more closely depicted, but which may be a screw conveyor, known in itself in this connection. At the same time, the lock feeder 5 feeds steam from the feed means 6 into the steaminy ch3mber 4.
The feed means 6 continuously pushes chips into the throat of the hot gr;nder 7 of enclosed design. The grinder 7 generates steam, of which part dep3rts along with the groundwood through the grinder's periphery. Another part of the steam escapes through the throat of the grinder, against the chip flow. Part of this steam, again, passes through the feed me3ns 6, the lock feeder 5, the steaming chamber 4, the lock feeder 3 and the chip m3gazine 1 into free atmosphere. Since th;s part o-f the steam runs completely counter-current to the chip flow, it serves efficiently to remove air from the system. Another part of the steam dischargin3 from the throat of the grinder 7 is conducted through the steam conduit 9, fitted ~ith throttling va~ve 8, into a heat exchanger 10, preferably of the condenser/evaporator type. The throttling valve 8 is used to controL the tempera-ture~n~fpressure in the grinder 7. The valve 8 is throttled to such extent that grinding will take place at a temperature not lower than 135 Centigrade, whereby the equivalent pressure in the gr;nder will be at least 350 kPa. In the trials performed up to now, no upper limit for the temperature or pressure has been found. It is obvious, at all events, that th~ usability of the steam g3ined from the process increases with increasing temperature and pressure. On the other hand, the temperature cannot be raised to any great height without damaging the fibres.
The groundwood derived from the grinder 7, which is accompanied by steam, departs from the grinder's periphery through the conduit 11 to the cyclone 12.
Here, the groundwood settles do~nwardly, and the steam goes through the steam conduit 14, provided with throttling valve 13, to the heat exchanger 10. The feed means 15 and grinder 16 may be of the same kind as the feed means 6 and grinder 7 presented before. The steam discharging from the throat of the grinder 16 against the groundwood flow goes through the feed means 15, cyclone 12 and steam conduit 14 to the heat exchanger 10.
The finished groundwood, accompanied by steam, departs from the periphery of the grinder 16 through the conduit 17 to the cyclone 18, hhere the steam .
,. . . . .
~ . ~ : . . .
~ PAGE 6 separates and goes through the conduit 20~ provided with throttling valve 19, to the heat exchanger 10. The groundwood settles do~"nwardly in the cyclone 1 and departs through the lock feeder 21 int~ tne conttl;ner 22, whence it may be transportad to any desired point~ It is clear that hereby a slight over-pressure prevails in the container 22, and ~hich discharges as the arro 23 shows. Hereby the entrance o-f air into the process is prevented. The dry matter content of the pulp in the container 22 is about 45~, or higher~
It is obvious to a person skilled ;n the art that different embodiments of the invention may vary within the scope of the claims following below. It has been disclosed in the foregoing, and d2monstrated in the drawing, that -the process co,nprises two consecutive grinders 7 and 16, but the invention may also be applied in connection with a process comprising in consecu-t;ve arrangement more than two grinders.
"~ : ,
Claims (5)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A process for preparing thermogroundwood from wood chips, wherein a flow of said wood chips is conducted from a storage magazine under normal pressure through a first lock feeder into a pressurized steaming chamber, where the ships reside for a few minutes and are heated to an optimum temperature of 100 to 125°C, and from the steaming chamber through a second lock feeder to a feed means which supplies the chips into an enclosed hot grinder to produce said thermogroundwood steam discharging from a throat of the grinder against the chip flow being arranged heat the chips in the steaming chamber, steam separated from the thermogroundwood being conducted to a heat exchanger, the steam for heating the ships being conducted in complete counter-current fashion to the chip flow, through the feed means, second lock feeder, steaming chamber, first lock feeder and magazine under normal pressure into the atmosphere, and the grinding of the chips being carried out at a substantially higher temperature than the heating of the chips.
2. A process according to claim 1, in which of the steam discharging from the throat of the grinder part flows to the heat exchanger said steam flow being strongly throttled to control the temperature of grinding in the grinder.
3. A process according to claim 1 or 2 in which grind-ing of the chips in the grinder is carried out at a temperature not less than 135°C.
4. An apparatus for preparing thermogroundwood for wood chips comprising in the direction of flow of said wood chips a chip storage magazine under normal pressure, a first lock feeder, a steaming chamber, a second lock feeder, a feed means and at least one hot grinder in which said thermogroundwood is produced, a cyclone for removing steam from the thermoground-wood being produced after each grinder each of which cyclones steam is arranged to conducted to a common heat exchanger, the feed means of a first grinder being connected by a steam conduit provided with throttling valve to the heat exchanger.
5. An apparatus according to claim 4 in which there are a plurality of consecutive grinders each followed by one said cyclone.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FI790106 | 1979-01-12 | ||
| FI790106A FI62149C (en) | 1979-01-12 | 1979-01-12 | FOERFARANDE FOER FRAMSTAELLNING AV VARMSLIPMASSA |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1114214A true CA1114214A (en) | 1981-12-15 |
Family
ID=8512300
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA343,494A Expired CA1114214A (en) | 1979-01-12 | 1980-01-11 | Procedure and means for preparing thermogroundwood |
Country Status (5)
| Country | Link |
|---|---|
| US (1) | US4421595A (en) |
| JP (1) | JPS55128089A (en) |
| CA (1) | CA1114214A (en) |
| FI (1) | FI62149C (en) |
| SE (1) | SE437680B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4999084A (en) * | 1988-08-12 | 1991-03-12 | Sulzer-Escher Wyss Gmbh | Method for heat treating short fiber fractions after separation of the long fiber fractions from a secondary fiber mixture |
Families Citing this family (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| SE441107C (en) * | 1982-05-07 | 1991-03-18 | Modo Chemetics Ab | PROCEDURES FOR PREPARING CHEAP HIGH-EXCHANGE MASS WITH GOOD PAPER CHARACTERISTICS |
| SE436287B (en) * | 1983-04-12 | 1984-11-26 | Sunds Defibrator | SET AND DEVICE FOR MANUFACTURING FIBER MASS FROM LIGNOCELLULOSALLY MATERIAL |
| JP2615545B2 (en) * | 1985-05-30 | 1997-05-28 | カシオ計算機株式会社 | Electronic musical instrument |
| US4925527A (en) * | 1989-02-22 | 1990-05-15 | Ahlstromforetagen Svenska Ab | Method for the recovery of turpentine and heat in a refiner pulping process |
| SE470575B (en) * | 1993-02-01 | 1994-09-19 | Sunds Defibrator Ind Ab | Methods for preparing fibrous pulp of lignocellulosic fibrous material where the fibrous material is first fed into and continuously passed through a preheater |
| SE518897C2 (en) | 2001-04-17 | 2002-12-03 | Lars Obitz | System and method for feeding fibers from a fiber separation step at a first pressure to a drying step at a second, lower pressure |
| FI20022050L (en) * | 2002-11-18 | 2004-05-19 | M Real Oyj | Method and apparatus for producing mechanical fiber |
| SE524788C2 (en) | 2003-02-11 | 2004-10-05 | Metso Paper Sundsvall Ab | Method and apparatus for producing and treating wood fibers |
| US7381303B2 (en) * | 2004-04-27 | 2008-06-03 | Honeywell International Inc. | System and method for controlling a thermo-mechanical wood pulp refiner |
| RU2407768C2 (en) | 2005-06-03 | 2010-12-27 | Андриц Аг | Method to reduce power consumption in production of thermomechanical wood pulp by means of low-temperature grinding of wood pulp of low and medium concentration |
| JP5060791B2 (en) * | 2007-01-26 | 2012-10-31 | 独立行政法人森林総合研究所 | Method for drying wood, method for penetrating chemicals into wood and drying apparatus |
| FI121816B (en) | 2009-01-08 | 2011-04-29 | Upm Kymmene Corp | Refiner and pulp refining process |
| FI122889B (en) | 2010-12-31 | 2012-08-31 | Upm Kymmene Corp | Method and apparatus for producing nanocellulose |
| US20200196658A1 (en) | 2018-12-20 | 2020-06-25 | R.J. Reynolds Tobacco Company | Method for whitening tobacco |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4059237A (en) * | 1974-02-15 | 1977-11-22 | Oy Keskuslaboratorio - Centrallaboratorium, Ab | System for feeding a double disc refiner |
| SE413601B (en) * | 1976-06-30 | 1980-06-09 | American Defibrator | SET FOR MANUFACTURING THE FIBER MASS IN A UNDERPRESSED MALAWARE AND DEVICE FOR IMPLEMENTATION OF THE SET |
| SE411562B (en) * | 1977-12-12 | 1980-01-14 | Forsberg G L K | SET FOR TREATMENT OF MASS GOODS WITH A GAS OR LIQUID FLUID AND DEVICE TO PERFORM THE SET |
| FI58953B (en) * | 1977-12-22 | 1981-01-30 | Valmet Oy | EXTENSION OF MEASUREMENT OF THERMAL MECHANICAL MASS OF BODY MACHINERY |
-
1979
- 1979-01-12 FI FI790106A patent/FI62149C/en not_active IP Right Cessation
-
1980
- 1980-01-11 JP JP145880A patent/JPS55128089A/en active Pending
- 1980-01-11 SE SE8000220A patent/SE437680B/en not_active IP Right Cessation
- 1980-01-11 CA CA343,494A patent/CA1114214A/en not_active Expired
-
1982
- 1982-02-01 US US06/344,624 patent/US4421595A/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4999084A (en) * | 1988-08-12 | 1991-03-12 | Sulzer-Escher Wyss Gmbh | Method for heat treating short fiber fractions after separation of the long fiber fractions from a secondary fiber mixture |
Also Published As
| Publication number | Publication date |
|---|---|
| US4421595A (en) | 1983-12-20 |
| SE8000220L (en) | 1980-07-13 |
| FI62149C (en) | 1984-03-20 |
| SE437680B (en) | 1985-03-11 |
| JPS55128089A (en) | 1980-10-03 |
| FI790106A7 (en) | 1980-07-13 |
| FI62149B (en) | 1982-07-30 |
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| MKEX | Expiry |